Improving thermo-rheological behavior and compatibility of SBR modified asphalt by addition of polyphosphoric acid (PPA).

With the aim of improving the compatibility, high and low temperature properties of SBR modified asphalt, polyphosphoric acid (PPA) was added to achieve a further modification in this study. The effects of PPA and asphalt composition on physical properties, viscoelastic behavior, creep and recovery behavior, cracking resistance, compatibility and morphology of PPA/SBR modified asphalt were characterized, respectively. It was demonstrated that PPA dramatically enhanced the adhesion ability, high temperature elasticity and anti-rutting ability of SBR modified asphalt through deflocculation effect. The resistance against low temperature cracking of PPA/SBR modified asphalt underwent a degradation after first improvement as PPA increased. PPA also improved the compatibility between SBR and asphalt and decreased the dispersed polymer phase size, thus a more desirable microstructure was formed. Furthermore, relatively high asphaltene content of base asphalt was beneficial to achieve desired rheological properties of PPA/SBR modified asphalt. As a consequence, chemical reaction with PPA is an effective way to comprehensively improve the compatibility and thermo-rheological behavior of SBR modified asphalt. [ABSTRACT FROM AUTHOR]